petMD Blogs

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.

Humans usually get plague after being bitten by a rodent flea that is carrying the plague bacterium or by handling an animal infected with plague. Plague is infamous for killing millions of people in Europe during the Middle Ages. Today, modern antibiotics are effective in treating plague. Without prompt treatment, the disease can cause serious illness or death. Presently, human plague infections continue to occur in the western United States, but significantly more cases occur in parts of Africa and Asia.

So, the possibility that your companion canine or feline could be exposed to the plague and pass the disease on to you, your human family members, or other pets is very real. The potential for zoonosis (transmission of illness among different species) is an important consideration for anyone inviting a pet into their home.

In 2011, USA Today featured the article Sleeping next to pets could be harmful, study says, which garnered significant attention among pet owners and those of us in the business of providing health care. In the piece, Bruno Chomel, a University of California Davis School of Veterinary Medicine professor, stated that close contact, such as that which occurs when pets sleep in our beds, could contribute to the spread of a variety of infectious organisms. Chomel noted Bubonic plague, Chagas disease (brought on by the protozoan Trypanosoma Cruzi), and cat scratch disease (caused by the bacteria Bartonella sp.) as the zoonotic diseases of concern.

Unfortunately, instead of emphasizing a common sense approach to pet care (see my tips below), this article struck fear into the hearts of pet owners by sending the message that our cats and dogs should be banished from the bedroom. According to Chomel, “There are private places in the household, and I think our pets should not go beyond next to the bed.”

Recently, plague-causing bacteria were identified in California ground squirrels that had been captured from two camp grounds in the San Diego area. According to a U-T San Diego story, Plague Found in Three Ground Squirrels, health officials are deterring people from having contact with squirrels and other wildlife.

Not every squirrel carries the plague, and there’s a low likelihood that people or other pets will encounter the bacteria from direct contact with squirrels. Yet, a bite from a plague-infected squirrel could potentially spread the disease. Generally, the disease spreading culprits are the fleas that take their blood meals from the squirrel. Chris Conlan, supervising vector ecologist for San Diego County’s Vector Control Program, said that "luckily, the fleas that are transferring plague from squirrel to squirrel much prefer to bite squirrels instead of people.”

Yersinia bacteria may be diagnosed in a few animals during routine surveys, yet no cases have occurred since 2011. The disease has some history in California. A Department of Public Health report lists 62 human plague cases in California from 1926 to 2013; 39 people survived and 23 died.

In general, using good sanitary habits can help prevent disease transmission from your pets or wildlife. My top five tips for keeping yourself and your animal and human family members free from undesirable pests include:

Avoid all contact between you and your pets with wildlife, and take measures to prevent both wild and roaming domesticated animals from entering your yard.

Comments 4

Living in Western Colorado, I have seen 3 cases of plague, all in cats, in my 38 years of practice here. Cats are much more susceptible to plague than dogs, and their hunting tendencies are more likely to bring them into contact with the animals that are the reservoirs for plague than dogs.

The disease runs in cycles with the years of no plague being more numerous than the years with plague, but when plague is around, it's very important for outside pets to have flea prevention for rodent fleas. (Around here we don't have regular dog and cat fleas!)

Even though dogs hardly ever get plague, they can harbor infected fleas that can then potentially be transferred to people with whom they come into contact.

The cats that I have seen with plague all had very high temperatures that didn't respond to antibiotics that we usually give them, like Amoxicillin. That arouses my suspicion, and if I haven't already checked, I look for enlarged lymph nodes, especially under the lower jaw and sores in the mouth and throat.

One of the cats that had plague was my own cat, and it contracted the disease in November which is unusual because fleas aren't usually a problem at that time of the year. She did fine with the proper antibiotics which are usually tetracycline or doxycycline.

Dr. Bob,
Thank you for sharing your clinical experience in diagnosing the plague among your patients.
I always find it valuable to learn of the experiences of other practitioners pertaining to the diseases they have faced in practice that I may be less aware of due to geography.
Dr. PM

One more reason to keep my kitties indoors. (Hopefully I won't bring any pests inside on my shoes... but then again, it helps not being an outdoor person!) I'm not sure I could sleep if I didn't have a critter or two lounging on my legs or neck.

It's good to be hyper-aware of the potential to bring infectious disease into your home and to take measures to prevent emergence of flea-borne illness through topical/oral treatments and instituting sanitary protocols to keep your home and pets flea-free.
Be proactive and your pets and other household humans will benefit!
Dr. PM